HNF6 Confers Resistance To Anoikis To Promote Colorectal Cancer Metastases

BackgroundColorectal carcinoma(CRC)is one of most common gastrointestinal malignancy,and becomes a severe threat to human health and development.The spread and metastasis of colorectal cancer is the most common cause of high mortality in patients.Research shows that about a quarter of patients have liver metastasis at the first diagnosis of colorectal cancer.And nearly half of patients would ultimately have liver metastasis.In addition,colorectal cancer also has pulmonary metastasis,bone metastases and brain metastases.HNF6 is one of the hepatocyte nuclear factor members(HNFs),involved in a variety of gene expression regulation as a transcription factor.Present research found HNF6 plays an important role in the formation and differentiation of pancreas,endocrine glands,bile duct,during the embryonic development.And some other research indicated that HNF6 also participates in occurrence,development and metastasis of liver cancer,breast cancer,and pancreatic cancer.But it is still unclear for the role of HNF6 in colorectal cancer.Our research group constructed HNF6 overexpression SW620 cell in previous study,and found that HNF6 result in changes of tumorigenicity and migration function.But the mechanism is not clear yet.MethodsWe analyzed the HNF6 different expression with GEO gene expression data from colorectal cancer,and verified it by immunohistochemistry of colorectal liver metastases pathological tissue from our research institute,to prove that HNF6 expressionhas been correlated with the colorectal cancer metastases.Then,we explored effects of HNF6 to the invasion and metastasis capacity in colon carcinoma cell with HNF6 overexpression SW620 cell constructed previously through experiments in vitro and in vivo.Finally,with the Western Blot analysis of HNF6 overexpression SW620 cell and the analysis of gene chip data,we preliminarily explored the probable mechanisms.Depending on all above studies and experiments,we can better understand the function of HNF6,and enrich the molecular mechanisms of colorectal cancer metastases.Results1.The expression of HNF6 is significantly higher in colorectal metastases than that in colorectal primary tumors,and the higher HNF6 expression is associated withpoorer prognosis.The HNF6 different expression with GEO gene expression data and colorectal liver metastases pathological tissue,indicated that expression of HNF6 was significantly higher in colorectal metastases than that in colorectal primary tumors,but non-involved in primary tumor location,size,differentiation,staging and tumor markers CEA.Survival analysis showed the patients with higher HNF6 expression was associated with poorer prognosis.2.HNF6 confers resistance to anoikis and promotes colorectal liver metastases.The results above showed that HNF6 expressionhas been correlated with the colorectal cancer metastases.We firstly constructed colon cancer metastasis nude-mouse models by respectively injection SW620-HNF6 cells and SW620-control cells to splenic subcapsular,and the results indicated that HNF6 promotes colorectal liver metastases.Then with the Transwell invasion assay,proliferative assay and plate clone formation assay,we found that HNF6 inhibits the migration,and improves the clonality.Then our research further showed HNF6 promoted anoikis resistance in colorectal cancer cell with anoikis experiment.Since the anoikis resistance is the basis of malignant tumor metastasis,we speculated that HNF6 promotes colorectal liver metastasis by anoikis resistance.3.The preliminary exploration of molecular mechanism that HNF6 confers resistance to anoikis and promotes colorectal metastases.The Western Blot analysis indicate the expression of Claudin-1,ZO-1 and Src were up-regulated in HNF6 overexpression SW620 colorectal cancer cells,and other metastasis correlation factors(β-catenin、E-cadherin、Vimentin、Snail)had no significant difference.According to other researches,Claudin-1 will form complex with ZO-1 and Src in colorectal cancer cells,and confers resistance to anoikis through the Src-Akt-Bcl-2.Then with theknock-down expression of Claudin-1 in SW620-HNF6 cells,we found a reversion on inhibition in the migration from HNF6.ConclusionThe expression of HNF6 is significantly higher in colorectal metastases than that in colorectal primary tumors,and the higher HNF6 expression is associated with poorer prognosis.The over expression of HNF6 facilitates complex of Claudin-1,ZO-1 and Src,and confers resistance to anoikis to promotes colorectal metastases.